So there's lots going on here.
And then we can add more layers of complexity, because actually,
although we can come up with the prototypical qualities of any one speech
sound, when we're linking sounds together, they actually
influence each other and the speech stream is a bit of a mush when it comes to it.
So, for example, if I'm making the R sound, that sound
will have a certain group of frequencies, a certain duration.
But then, if I put an M at the end, so [SOUND],
then actually I'm really altering the quality of
the [SOUND] in my preparation to make that [SOUND] sound.
So the vowel is actually getting influenced by the nasal
quality of the [SOUND].
And yet our brains just makes sense of this.
They extrapolate, they work out, okay that's still an R,
even though it's being a bit intruded by the [SOUND].
So it's an epic feat that our brains are doing, distinguishing sounds at all.
And so, this suggests that then actually there's multiple levels
at which the system could also go wrong.
And I think this is the conundrum around the relationship between auditory
perception and phonological processing difficulties in dyslexia.
Because lots and lots of researchers have been looking at this area, but
they've all taken a slightly different aspect of this perceptual task.
They've perhaps used children, looked at children with different ages, and
a different dyslexia profile potentially given the heterogeneity of dyslexia.
So I often think about the story of the blind men and
the elephant when trying to kind of make sense of this.
Because it feels like auditory perception is this elephant and
us researchers are blindly holding on to a different aspect of it and
thinking this is maybe the thing that's going wrong.
And so, then people are thinking, well, I'm finding different things to you.
But actually, we're probably all looking at aspects of the same issue.
So, to summarize where the research is at in this area, what we seem to find is
that when people do studies of different aspects of auditory perception and
seeing if these are impacted in dyslexia, we're finding that typically
most studies find that a sub group of children do struggle with,
say, duration discrimination, or loudness discrimination.
But it's never typically seen in all the children with Dyslexia
in a research sample.
So this suggests to us that auditory perception does
sometimes seem to be compromised, but it's not a consistent link.
We can't clearly say the phonological problem is
incontrovertibly coming from a lower level auditory cause.
But this doesn't mean that that's actually not what is happening.
And if you remember when I was talking about a longitudinal
study in Finland where they'd actually followed children had genetic
risk from dyslexia from the first week of life.
And by playing the infant's Finish speech syllables and
looking at the neural responses to those syllables, they were finding strong
correlations to later language development and later reading development.